Quantifying nitrous oxide production rates from nitrification and denitrification under various moisture conditions in agricultural soils: Laboratory study and literature synthesis

Abstract

Biogenic nitrous oxide (N2O) from nitrification and denitrification in agricultural soils is a major source of N2O in the atmosphere, and its flux changes significantly with soil moisture condition. However, the quantitative relationship between N2O production from different pathways (i.e., nitrification vs. denitrification) and soil moisture content remains elusive, limiting our ability of predicting future agricultural N2O emissions under changing environment. This study quantified N2O production rates from nitrification and denitrification under various soil moisture conditions using laboratory incubation combined with literature synthesis. 15N labeling approach was used to differentiate the N2O production from nitrification and denitrification under eight different soil moisture contents ranging from 40 to 120% water-filled pore space (WFPS) in the laboratory study, while 80 groups of data from 17 studies across global agricultural soils were collected in the literature synthesis. Results showed that as soil moisture increased, N2O production rates of nitrification and denitrification first increased and then decreased, with the peak rates occurring between 80 and 95% WFPS. By contrast, the dominant N2O production pathway switched from nitrification to denitrification between 60 and 70% WFPS. Furthermore, the synthetic data elucidated that moisture content was the major driver controlling the relative contributions of nitrification and denitrification to N2O production, while NH4+ and NO3− concentrations mainly determined the N2O production rates from each pathway. The moisture treatments with broad contents and narrow gradient were required to capture the comprehensive response of soil N2O production rate to moisture change, and the response is essential for accurately predicting N2O emission from agricultural soils under climate change scenarios.

Sediment Addition Leads to Variable Responses in Temperate Salt Marsh Greenhouse Gas Fluxes During the Growing Season

“…The best model for predicting N 2 O included experimental block as a random effect and soil moisture as a fixed effect. This relationship between N 2 O and soil moisture has been documented in the literature and is driven by changes in soil moisture impacting oxygen concentrations that than drive varying rates of nitrification and incomplete denitrification (Burgin & Groffman, 2012; Wang et al., 2023). Exploring the CO 2 and CH 4 model results more we see that many of the significant parameters were related to the hydrology.…”

Plants reduced nitrous oxide emissions from a Northern Great Plains saline/sodic soil

“…If it is assumed that N 2 O‐N emissions reflect nitrification in the productive soil and denitrification in the saline/sodic soil, then these predicted decreases were much lower than the observed barley‐induced N 2 O‐N decreases of 70% and 84.8% in the productive and saline/sodic soils, respectively. Large differences between the measured (>70% reduction) and predicted (14%–36% reduction) emissions suggest that other factors than just water‐filled pore space (Bateman & Baggs, 2005; Linn & Doran, 1984; Wang et al., 2023) contributed to plant‐induced N 2 O‐N decreases. For example, D. J. Fiedler et al.…”

Identification and apportionment of groundwater nitrate sources in Chakari Plain (Afghanistan)

“…The natural concentrations of NO3̄ in aquatic environments occurs at concentrations commonly no higher than 3 mg L‾ 1 as NO3-N. Higher concentrations of NO3̄ in aquatic systems are generally the result of anthropogenic activities associated with extensive utilization of artificial fertilizers, manure and sludge in agricultural land, or discharge of urban and industrial wastes and leaching from landfills of solid waste (Kendall et al, 1998;Galloway et al, 2004;Voss et al, 2006;Kendall et al, 2007;Stadler et al, 2008 Discharge of wastewater and contaminated groundwater with elevated levels of NO3̄ into surface water bodies can cause several environmental and ecological problems, such as eutrophication of streams, reservoirs, estuaries, lakes, and blooms of toxic algae (Galloway et al, 2004;Qin et al, 2018;Zhu et al, 2019;Kaown et al, 2023). In addition, high concentrations of nitrate in aquatic systems increases anthropogenic biogenic nitrous oxide emissions in the atmosphere (Wang et al, 2022). Moreover, high concentrations of NO3-N (> 10 mg Lˉ1) in drinking water can lead to blue baby syndrome (methemoglobinemia) in infants, damage to DNA and might also be a contributing factor to some cancer types (Fan and Steinberg, 1996;Fewtrell, 2004;Ward et al, 2005;Davidson et al, 2011;Nikolenko et al, 2017;.…”